Bioimpedance-based authentication of defrosted versus fresh pork at the end of refrigerated shelf life Publié en ligne: 14 janv. 2023 Pages: 125 - 131 Reçu: 29 sept. 2022 © 2022 Daniel E. Osen, Sisay Mebre Abie, Ørjan G. Martinsen, Bjørg Egelandsdal, Daniel Münch, published by Sciendo This work is licensed under the Creative Commons Attribution 4.0 International License.
Figure 2 Individual impedance response spectra and Py values indicate almost complete separation of refrigerated and subsequently frozen-thawed pork samples (N=20 for each test group and one specific electrode position). A. Impedance spectra before freezing (refrigerated) and after thawing (frozen-thawed). B. Histogram plot of Py values for all pork sirloin samples, as extracted from one specific position measurement. Figure 1 Measuring the bioimpedance of sirloin cuts. Four different positions were chosen for the electrode, two with the electrode inserted perpendicular to the anterior-posterior axis of the LTL (A, B; approximately also perpendicular to the main muscle fiber direction) and two positions along the anterior-posterior axis (C, D; approximately in line with the main muscle fiber direction C, D). The side facing the camera is the dorsal side of the LTL muscle (depicted axes: anterior/posterior & left/right). Figure 3 Individual impedance phase angle responses in pork before and after freezing-thawing (N=20 per treatment group). A. The phase angle of refrigerated and frozen-thawed meat measured in one specific position. B. The distribution of phase angle values at 110 kHz reveals apparent differences between refrigerated and frozen-thawed samples. Summary of the analyzed full factorial design (ANOVA) with Py as response and a two-level factor encoding for potentially confounding effects (R/FT = refrigerated/frozen-thawed; On/Al = electrode position ‘on-top’ into back muscle/see Fig. 1C, D versus ‘along’, through back muscle/see Fig. 1A, B; Pos = Position of electrode, left and right side of the sample; * = p > 0.2).
Py
Variables
Explained variance (adj.) (%)
p-value
Main factors
R/FT
12.8
<0.001
On/Al
-
*
Pos
0.2
0.051
Interaction
F/FT. On/Al
-
*
F/FT. Pos
1.4
0.106
On/Al.Pos
-
*
Covariates
Driploss (22.5 ± 1.2g)
-
**
Weight (335.4 ±7.4g)
3.7
0.009
pH (5.22 ± 0.01)
-
*
Error
79.5
-